[FFmpeg-devel] [PATCH]Ignore xing number of frames if filesize is wrong

[Carl Eugen Hoyos]

Hi!

Attached patch fixes ticket #3777 for me, analyzed by Oliver Fromme.

Please comment, Carl Eugen
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diff --git a/libavformat/mp3dec.c b/libavformat/mp3dec.c
index 8335388..cdef6d9 100644
--- a/libavformat/mp3dec.c
+++ b/libavformat/mp3dec.c
@@ -138,6 +138,7 @@ static void mp3_parse_info_tag(AVFormatContext *s, AVStream *st,
 
     MP3DecContext *mp3 = s->priv_data;
     static const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
+    int64_t fsize = avio_size(s->pb);
 
     /* Check for Xing / Info tag */
     avio_skip(s->pb, xing_offtbl[c->lsf == 1][c->nb_channels == 1]);
@@ -151,6 +152,9 @@ static void mp3_parse_info_tag(AVFormatContext *s, AVStream *st,
         mp3->frames = avio_rb32(s->pb);
     if (v & XING_FLAG_SIZE)
         mp3->header_filesize = avio_rb32(s->pb);
+    if (fsize > 0 && mp3->header_filesize > 0 &&
+        FFABS(fsize - (int64_t)mp3->header_filesize) / (float)FFMIN(fsize, mp3->header_filesize) > 0.05)
+        mp3->frames = 0;
     if (v & XING_FLAG_TOC)
         read_xing_toc(s, mp3->header_filesize, av_rescale_q(mp3->frames,
                                        (AVRational){spf, c->sample_rate},